"There is reason to believe that a crime has been committed," read a statement from Marianne Ny, Sweden's director of public prosecutions. "Considering information available at present, my judgment is that the classification of the crime is rape."

She said more investigation is necessary before she can make a final decision.

An ongoing investigation about a separate charge of molestation will be extended, she added, but the charge will also be escalated to include a sexual component.

The molestation charge was previously equivalent to a non-sexual charge of harassment, but it will now come under the heading of sexual coercion and sexual molestation, which are both crimes, she said.

Assange's lawyer, Leif Silbersky, said he and his client were "very surprised" at the decisions.

"It's unbelievable," he told CNN. "We thought that this circus had ended. Now it's happening all over again."

Prosecutors questioned Assange for about an hour on Monday, though only about the complaint of molestation, Silbersky told CNN. He said police never mentioned the rape allegation during that questioning.

"He maintains that he is completely innocent," Silbersky said.

Silbersky said he has not been shown anything about the rape allegation and is not sure what the next step is.

Swedish authorities arrested Assange "in absentia" last month on charges of rape and molestation. The chief prosecutor later revoked the arrest warrant and dropped the rape charge. The charges came from two separate women.

The lawyer for both women appealed, asking for the rape charge to be reinstated and the molestation charge to be upgraded to include a sexual component.

Before he was questioned, Assange told CNN he had no idea what the case was about.

Assange told the Arabic-language television network Al-Jazeera August 22 the accusations are "clearly a smear campaign." The only question, he said, is who is behind it.

The allegations follow WikiLeaks' release last month of 76,000 pages of U.S. documents related to the war in Afghanistan. U.S. Defense Secretary Robert Gates has criticized the leak, saying it would have a significant negative impact on troops and allies, revealing techniques and procedures.

Assange has defended the leak, saying it can help shape the public's understanding of the war. He said the material was of no operational significance and that WikiLeaks tried to ensure the material did not put innocent people at risk.

The attorney for the alleged victims has told CNN that rumors of possible Pentagon or CIA involvement in the sex crime accusations against Assange are "complete nonsense."

CNN's Atika Shubert in Amsterdam, Netherlands, contributed to this report.